For months, Mitt Romney’s campaign has expressed confidence in its ability to restore North Carolina to the Republican column in November. The boast isn’t just bluster. With five consecutive polls showing Romney ahead by an average of 5.6 points in North Carolina — which Barack Obama carried by 14,000 votes in 2008 — the Romney campaign on Thursday signaled it would begin redeploying resources to tighter battlegrounds. On the day early voting kicked off in the Tar Heel State, RealClearPolitics (RCP) shifted the state from toss-up status to “lean Romney.”

One can question whether such confidence is misplaced, but the shift is a sign we have entered a new phase of the campaign, marked by a final sprint around a shrinking battlefield. Since the start of the general election, and even amid the jagged vicissitudes of the past six weeks, the electoral map has been remarkably static. Romney and Obama have spent the vast majority of their time and money in just nine states: Colorado, Florida, Iowa, Nevada, New Hampshire, North Carolina, Ohio, Virginia and Wisconsin. From time to time, polls have given rise to rumors that another state (Pennsylvania, Michigan or Arizona, for example) might come into play, but it doesn’t look that way. Now, if North Carolina is sliding to Romney’s column — a judgment the Obama campaign disputes — we are down to eight.

In fact, the number of states up for grabs is probably even smaller. And while Romney has a narrow but steady lead in the polls, Obama boasts the advantage in the Electoral College math. Romney’s problem is that he has fewer pathways to 270 electoral votes. As National Journal‘s Major Garrett explains:

Romney, according to RCP, has 191 electoral votes. If you add Florida (29), North Carolina (15), and Virginia (13), that brings his total to 248 electoral votes. Add Colorado (9) — which neither campaign is prepared to claim or concede — and Romney’s total rises to 257 electoral votes. If Romney wins Ohio (18) in addition to these states, he would have 275 electoral votes. If Romney loses Ohio, he would need to win Iowa, Nevada, and New Hampshire to reach 273 electoral votes. There is a scenario where Romney could lose Ohio and New Hampshire but win Iowa and Nevada and one electoral vote from the 2nd Congressional District in Maine (the state allocates electoral votes by district vote) and capture the bare minimum of 270 electoral votes.

If you give Romney North Carolina, he has 206, but he still needs to carry Virginia and Florida, plus wrest away several from a grab bag of swing states Obama won in 2008 to vault his campaign over the hump. These include two Mountain West toss-ups (Colorado and Nevada, the latter of which seems to lean toward Obama), New Hampshire (where Obama is a 70% favorite, according to Nate Silver’s algorithm) and three Midwestern states (Iowa, Wisconsin and Ohio) where the incumbent has held slim but steady leads.

The Buckeye State, a perennial presidential bellwether, is again the linchpin for both sides. If Romney doesn’t win Ohio, Obama senior adviser David Plouffe said recently, “he’s not going to be President.” And for all the Republicans’ talk about surging enthusiasm and strong early voting and rosy internal polls, Ohio — where 1 in 8 jobs is tied to an auto industry Obama nursed back to relative health — will be a hard get for the GOP.